Rolling Thunder is an interesting operation to investigate, because the bombing strategy changes over time.

A little bit of background:

After Geneva conference in 1954, the U.S. replaces France as a political backup for Ngo Dinh Diem in the South Vietnam. They believed in the “domino effect”, which suggested that if Vietnam fell under the influence of communism, all countries around would follow. At first, the U.S. believed South Vietnam’s government could be grown into a self-sustained one. However, by the beginning of 1965, that belief was turned into “without further American action, Saigon government could not survive.”

Operation Rolling Thunder was devised as a demonstration of such commitment to Saigon.

The operation lasted from 1965-03-02 - 1968-11-02 with three main objectives which evolved over time:

What is interesting here is that the U.S. tried to “tread on thin ice”. They wanted to scare North Vietnam off the South, but they did not dare to go for a full-blown air campaign lest China or Soviet would retaliate with their full might. Therefore, their bombing strategy slowly escalated and changed over time, which would reflect to the data.

Overview

As shared above, the operation started from beginning of 1965. However, we only have data from October of the same year. During this operation, a total of 419,775 ton of weapons were dropped on Vietnam.

To minimize airspace conflict among air forces, North Vietnam was divided into six target regions called “route packages” (RP:

Each region was assigned to one air force or navy, and they were forbidden to intrude each others’ regions. The Navy’s Carrier Task Force 77 handled operations in RP 2, 3, 4, and 6B, as these bordered on the Gulf of Tonkin. The Air Force was given RP 1, RP 5, and 6A. We can see this division clearly from the bombing targets:

Evolution of bombing targets

At the beginning of the operation, Washington believed in “gradualism”, which considered “the threat of destruction is a better signal of U.S.’ determination than the destruction itself”. This translated into the the U.S. strategy to “hold important target hostage by bombing trivial ones”. Johnson tightly control the campaign, refused to attack Hai Phong port directly and he deemed it “too provocative”.

We can see this initial hesitation clearly when looking at bombing map of 1965:

According to air force historian Earl Tilford:

“(Initially) Targeting bore little resemblance to reality in that the sequence of attacks was uncoordinated and the targets were approved randomly – even illogically. The North’s airfields, which, according to any rational targeting policy, should have been hit first in the campaign, were also off-limits.”

This course of action angered the military generals. They were disatisfied with the ranndomness and uselessness of the targets, and complained that striking and re-striking some targets benefited the North Vietnam’s defense force. Thanks to the repetiveness of targets, Vietnamese gunners got time to adapt to U.S. patterns and incured heavy lost on its air forces. To calm these concerns, from mid 1966 to 1967 President Johnson approved attacks on sensitive targets, especially targets in Hanoi and Hai Phong.

In 1968, Rolling Thunder reached its final stage of operational evolution. Its purpose transformed from psychological warfare in the higher route packages to that of interdicting the logistics flow from the North to the South.

Let’s look at the change of U.S. bombing priorities throughout the years again:

## nframes and fps adjusted to match transition
## nframes and fps adjusted to match transition

Details on bombing stragegies

Bombing tonnage in increased gradually year-by-year and peaked in 1968, which is why it was described as the bloodiest year in this war.

The increase in intensity also reflects in the tonnage over area. During the peak bombing time of 1968, each square kilometer received more than three times the amount of weapon in the previous peaks. This was due to the increase in bombing tonnage, and the higher focus of targeted area.

Most of the sorties are related to Strike and Armed reconnaissance missions. While targets of Strike missions were fixed, Armed recon missions’ targets are situational. This type of mission made use of small aircraft formations to patroll highways, railroads, rivers and bombed whatever they deemed necessary.

During 1966 there was a huge spike in the number of armed recon missions. This was most likely due to the military’s complain about the complicated system to request fixed targets. Even in the later years the number of this mission type is still constant, and is only surpased by Strike missions when the U.S. bombing efforts escalated.

Aircraft used in these kind of missions:

What’s the use of different aircrafts over time?

Attack aircrafts were use more and more, indicating more precise bombing missions. Meanwhile, pure fighter aircrafts used less or were adapted into fighter - bomber roles. By this time, dogfighting (air-to-air combat) were fallen out of favor in the U.S. This is due their belief that missiles were all they needed to shoot down Soviet’s heavy bombers, and official dogfight training only returned by 1969 with the TOPGUN program.

Aircrafts

Fighter-bomber: F4 & F105

The McDonnell Douglas F-4 Phantom II is an all-weather, long-range fighter-bomber originally developed by the U.S. Navy. This aircraft was proved to be highly adaptable, so it was adopted by USAF, USMC and USN.

What is a fighter-bomber? According to Wikipedia:

A fighter-bomber is a fighter aircraft that has been modified, or used primarily, as a light bomber or attack aircraft. It differs from bomber and attack aircraft primarily in its origins, as a fighter that has been adapted into other roles, whereas bombers and attack aircraft are developed specifically for bombing and attack roles.

Probably due to this versatility, fighter-bomber type had the highest number of sorties and dropped the second-highest tonnage of bombs.

The F4 and F105 were used mainly by U.S. Air Force, while the F4 were also used by U.S. Navy and Marine Corp.

According to Wikipedia, “It (F-4) served as the principal air superiority fighter for the U.S. Air Force, Navy, and Marine Corps and became important in the ground-attack and aerial reconnaissance roles late in the war”. U.S. Navy were mainly responsible for the development of this aircraft and then distributed it to the USAF and USMC with great expectation about its performance.

We can see the F-4’s growing usage over time. Meanwhile, the F-105 was later removed from combat due to high loss rates.

Attack aircraft: A1, A4 & A6

The A-1 Skyraider was an attack aircraft that was transfered to RVNAF and remained as its “close air support workhorse” for much of the Vietnam War.

The use of A-1 gradually decreased over time as it was to be replace by the A-6A Intruder and A-4 Skyhawk as part of the general switch to jet aircraft.

Target types

Bridge, depot and road were bombed most heavily.

Motor vehicles were target more in the final stage of the operation - this probably correspond with the U.S. effort to cut the support line from the North to the South.

Regrettably we do not have data of 1965, but we can still see POL targets were bombed with much higher intensity at the beginning but then went out of focus. According to Wikipedia:

On 29 June 1965, airstrikes against the North’s petroleum, oil, and lubricants (POL) storage areas were finally authorized by Johnson. Howerver, North Vietnam’s army anticipated this move and spread their POL reservoir across the whole country. By 4 September 1965, POL strikes was halted as U.S. intelligence realized that the North suffered no POL shortage.

Outcome of the war

With the slow escalation of war, the Vietnamese army had time to adapt to the U.S. new strategies. Vietnamese signals intelligence staff of 5,000 were also “proved adept at exploiting traffic analysis as NSA was”, when they deduced that before every bombing mission had an upsurge of traffic involving logistics and recon flights. Interestingly, they were also able to intercept U.S. radio communication, which used unencrypted voice. This is a major source of early warning for the Vietnamese army. :

“…captured documents showed that the North Vietnamese had at least thirty to forty-five minutes’ warning of 80 to 90 per cent of Rolling Thunder missions.”

This severe security problem were not unknown to the U.S. Air Force, but they underestimated Vietnamese army’s intelligence capabilities and ignored NSA’s request to install voice encryption on aircrafts.

In short, Rolling Thunder was meant to “send a message” to the North, but it was not successful at what it set out to do.

Reference